Optical recording medium and method of information recording/reading an optical recording medium

ABSTRACT

An optical recording medium which includes a PMA area, a TOC area, program area, an area that includes a user area and lead-out area. A portion of the PMA area, which relates to the program area, is in a recorded state and the TOC area is in an unrecorded state. Alternatively, the PMA may be in an unrecorded state. In addition, a password may be recorded in a portion of an information area. A method of erasing the medium and a system for reading and recording information are also provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical recording medium capable ofretaining the secrecy of stored information and to a method of erasing,recording, and reading the stored information while retaining a highlevel of secrecy.

2. Discussion of the Background

Optical recording media are disc-shaped media capable of being read andrecorded to by optical devices. For example, Compact Discs (hereinafterreferred to as CDs) such as a Compact Disc Digital Audio (CD-DA), aCompact Disc Read Only Memory (CD-ROM), a Compact Disc Recordable(CD-R), and a Compact Disc ReWritable (CD-RW), or large capacity opticalrecording media such as a Digital Video Disc Read Only Memory (DVD-ROM),a Digital Video Disc Recordable (DVD-R), and a Digital Video DiscReWritable (DVD-RW) are well known. These media have become wide spreadas information recording and transmitting media. In particular, CD-RWmedia have become remarkably wide spread as erasable/rewrite-able CDmedia.

When these optical media are used as information-transmitting media, itis often important to keep information stored within the media secret.For example, data stored in a CD can be easily read by a commerciallyavailable CD drive or CD player. Therefore, a problem which occurs isthat secret information is easily leaked when an optical recordingmedium used to store the secret information is read by an unauthorizedperson.

The CD-RW media can be reused by erasing information which has beenstored. Information erasing methods for CD-RW include a full-erasemethod in which all the recorded data is erased and a quick-erase methodin which only control data is erased. Control data is necessary to allowa CD drive to access the information stored in the data area of a CD-RW.The quick-erase method is used in order to quickly make a CD mediumready for rewriting.

FIGS. 4A and 4B are schematic diagrams illustrating area-structures of aCD-RW medium before and after information is erased by a quick-erasemethod, respectively. A prior art erase method is described hereinafterreferring to FIGS. 4A and 4B.

In FIG. 4A, reference numerals 41, 42, 43, and 44 designate a programmemory area 41 (hereinafter referred to as a PMA), a table of contentsarea 42 (hereinafter referred to as a TOC area), a program area 43, anda lead-out area 44, respectively.

User information is stored in the program area 43 of the CD-RW mediumshown in FIG. 4A and a CD-RW drive gains access to the information inthe program area 43 on the basis of control data recorded in the PMA 41.After the control data is additionally recorded in the TOC area 42 andthe lead-out area 44, the information recorded in the CD-RW mediumbecomes capable of being read by a CD drive such as a CD-ROM drive. Thisrecording operation is performed using a CD-RW drive.

When the described quick-erase method is used, all of the control datastored in the filing information areas, i.e., the PMA 41, the TOC area42, and the lead-out area 44, are erased. The user information recordedin the program area 43 remain intact. However, there are no CD drivesavailable which can read the user information stored in the program area43, because there is no control data in the filing information areas.

Accordingly, there are currently no methods to read user informationstored in the program area 43 of a CD-RW medium when the medium isaccidentally erased by a quick-erase method.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above-discussedproblems and an object of the present invention is to address and solvethese and other problems.

The present invention provides an optical recording medium whichincludes an information area. The information are is comprised of a dataarea, in which user information can be stored, and a filing informationarea, in which control data for access to the user information can bestored. Initially, the data area is in a recorded state and the filinginformation area is in an unrecorded state.

The optical recording medium may further include a password that isrecorded in a portion of the information area.

The optical recording medium may be a CD-R or a CD-RW which includes aninformation area comprising a data area and a filing information area.The data area includes a program area in which user information isstored and a user area in which information can be stored. The filinginformation area contains control data used in accessing the stored userinformation. The filing information area includes a PMA, a TOC area, anda lead-out area. The user area, the TOC area, and the lead-out area arein an unrecorded state. Both the program area and a portion of the PMAare in a recorded state. The optical recording medium may furtherinclude a password that is recorded in a portion of the informationarea. When the medium is used as an information recording/reading systemhaving system information that is peculiar to the system, the systeminformation may be recorded in the medium. In this case, the systeminformation is used as a password, and the verification of the passwordmay be done by the information recording/reading system automatically.Specifically, when the system information is recorded in the data area,then control data for access to the system information may be furtherrecorded in the PMA.

In another aspect of the present invention, an erase method for erasingCD-RW media is provided, which includes the steps of reading controldata stored in a filing information area of a CD-RW medium, recordingthe control data in another medium, and erasing only the control data inthe filing information area of the CD-RW medium.

In still another aspect of the present invention, an informationrecording/reading system is provided which includes an optical recordingmedium which includes a file information area. The file information areaincludes a PMA which is in an non-recorded state and a program area inwhich user information is stored; a control data storing medium whichstores control data for access to the user information stored in theprogram area; and a recording device which records the control data inthe PMA. The optical recording medium may be a CD-R medium or a CD-RWmedium.

BRIEF DESCRIPTION OF DRAWINGS

A more complete appreciation of the present invention and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is a schematic view illustrating an embodiment of the opticalrecording medium of the present invention;

FIG. 2 is a schematic view illustrating another embodiment of theoptical recording medium of the present invention;

FIG. 3 is a schematic view illustrating yet another embodiment of theoptical recording medium of the present invention which has a high levelof secrecy;

FIGS. 4A and 4B are schematic diagrams respectively illustratingstructures of a CD-RW medium before and after information is erased by aquick-erase method;

FIG. 5 is a schematic diagram illustrating a structure of an embodimentof the optical recording medium of the information recording/readingsystem of the present invention.

FIG. 6 is a block diagram illustrating another embodiment of theinformation recording/reading of the present invention; and

FIG.7 is a flow chart illustrating an embodiment of the erase method ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, and moreparticularly referring to FIG. 1 thereof, there is shown an embodimentof the optical recording medium 10 of the present invention. The opticalrecording medium 10 may be, for example, a CD-R medium. Alternatively,the optical recording medium 10 may be a CD-RW medium. At the center ofthe optical recording medium 10, a hole 11 is provided which is capableof receiving the pivot of a CD drive. The optical recording mediumincludes an information area comprising a PMA 13, a TOC area 15, aprogram area 17, and an area 19 which includes a recordable user areaand a lead-out area disposed one by one from the inside to the outsideof the optical recording medium. The PMA 13 is further comprised of arecorded area 52 in which PMA data are recorded and an unrecorded area50. The TOC area 15 and the area 19 are also in an unrecorded state.Prescribed user information or requested user information is stored inthe program area 17.

The optical recording medium 10 shown in FIG. 1 includes the PMA 13, theprogram area 17 in an recorded state, and the TOC area 15 and the area19 that are in an unrecorded state and in a record-able state. Inaddition, the portion 52 of PMA 13, which relates to the program area17, is in a recorded state. The PMA 13, the TOC area 15, and thelead-out area are referred to as a file information area. The programarea 17 and the user area are referred to as a data area.

Control data and user information can be recorded in the PMA 13 and theprogram area, respectively, using a CD writing drive, such as, forexample, a commercially available CD-R or CD-RW drive. Alternatively,the medium 10 may be a hybrid-type medium that includes a record-ablearea and a ROM (read only memory) area in which pits corresponding touser information are previously formed using a stamper. In addition, themedium 10 may further include an additional area such as a PCA (powercalibration area).

Even in the undesirable case in which an unauthorized user intends toread user information stored in the program area, the outsider cannotread or play the optical recording medium of the present invention by aCD player or a CD-ROM drive. This is because CD players or CD-ROM drivescannot read information stored in a CD medium if control data is notrecorded in the TOC area 15. Therefore, the secrecy of the userinformation stored in the program area of the optical recording medium10 can be maintained against an unauthorized user who does not have a CDwriting drive.

An authorized user can read the user information by finalizing theoptical recording medium using a commercially available CD writingdrive. The CD writing drive reads the PMA data recorded in the PMA 13and then records TOC data in the TOC area 15 in accordance with the PMAdata. At the same time, the CD writing drive records lead-out data inthe lead-out area. The medium 10 can now be read by commerciallyavailable CD drives. After this finalization of the medium 10, aselected person can read information stored in the medium using a CDwriting drive and a CD player or a CD-ROM drive.

An information transmitting method using such an optical recordingmedium 10 is useful for a circle consisting of limited members in whichlimited user information is distributed to the members. The individualmember possesses a CD writing drive to read the user information.Information providers such as a bank, a stockbrokerage company, or aresearch company records user information for the limited members in theprogram area 17 of the optical recording medium 10 as shown in FIG. 1,and distributes the recorded medium 10 to each member. Because themedium 10 as distributed cannot be read with a commercially available CDplayer or a CD-ROM drive, secrecy of the distributed information issecure even when the medium 10 passes into a person other than themembers, for example, by miscarriage or robbery.

In this case, the information stored in the medium 10 can be read if anoutsider has a CD writing drive. The present invention provides anotheroptical recording medium detailed below in which information storedtherein cannot be read even in such a case.

FIG. 2 shows another embodiment of the optical recording medium 20 ofthe present invention. At the center of an optical recording medium 20,a hole 21 in which a pivot of a CD drive can fit is provided. Theoptical recording medium includes an information area having a PMA 23, aTOC area 25, a program area 27, and an area 29 comprising a recordableuser area and a lead-out area. The medium 20 may further include anadditional area such as a PCA (power calibration area). The PMA 23 isdisposed in an innermost portion of the medium 20, and the PMA 23, theTOC area 25, the program area 27, and the area 29 are disposed one byone in an outward direction.

The TOC area 25, the area 29, and the PMA 23 are in unrecorded state andin a recordable state. Prescribed user information or requested userinformation is already recorded in the program area 27. In addition, apassword may be recorded in a predetermined portion of the opticalrecording medium 20. The predetermined portion may be in the informationarea or a portion inside the information area such as, for example, aportion outside the lead-out area, the innermost portion of the TOCarea, or the innermost portion of the PCA, etc.

Specifically, the optical recording medium 20 shown in FIG. 2 includesthe PMA 23, the TOC area 25, the program area 27 that is in a recordedstate, and the area 29 having the user area and the lead-out area,wherein the PMA 23, the TOC area 25, and the area 29 are in anunrecorded state and in a record-able state. The password may berecorded in a specific portion of the medium 20.

Before the medium 20 is distributed to members of the group consistingof limited members mentioned above, the information provider notifieseach member of a password that is the same for all the members, and bywhich the information stored in the medium 20 can be read. The provideralso notifies the member of PMA (control) data corresponding to the userinformation recorded in the program area 27.

The group member sets the distributed medium 20 in a CD writing driveand inputs the notified password. The CD writing drive compares theinputted password with the password stored in the specific portion ofthe medium 20. When the inputted password is verified, the drive becomesable to write to medium 20.

Next, the member records the correct PMA data in the PMA 23 using the CDwriting drive. The member finalizes the medium 20 by recording TOC datain the TOC area 25 corresponding to the recorded PMA data.Alternatively, the member may finalize the medium using a computerinstalled with software for directly recording the TOC data in the TOCarea. In this case, the member inputs the notified PMA data to thecomputer. By this procedure, the finalized optical recording medium 20becomes readable or playable by CD drives.

In addition, when the information provider distributes specificinformation to a specific group member, other than common userinformation available for every member, another optical recording medium30 of the present invention as shown in FIG. 3 may be used. An area 29Aof the optical recording medium 30 is a portion in the program area inwhich specified information is additionally recorded by the providerusing a CD writing drive. PMA data regarding the additionally recordedportion of the program area is distributed to the specified member. Themember then inputs the password and the specific PMA data to finalizethe medium 30. Thus the medium 30 becomes readable or playable by CDdrives.

Even if the medium 30 is handed to an unauthorized user, theunauthorized user cannot read the user information, because the outsideris not notified of the password nor the PMA data regarding theadditionally recorded portion. Therefore, the secrecy of the informationcontained within medium 30 is maintained at a high level.

In addition, when a specific password is provided for a specified memberother than the common members, the specific password may be used tocover a variety of access ranks among the members. In this case,information relating to the additionally recorded portion of PMA can beread using the specific password. Accordingly, the specific informationis not disclosed to members having a lower access rank, thus increasingthe level of secrecy by limiting information access within the groupitself.

FIGS. 4A and 4B are schematic diagrams respectively showing structuresof a CD-RW medium before and after information is erased by aquick-erase method of the present invention. With reference to FIGS. 4Aand 4B, one embodiment of the erase method according to the presentinvention is described hereinafter.

In FIG. 4A, reference numerals 41, 42, 43, and 44 designate a PMA area,a TOC area, a program area (data area), and a lead-out area,respectively.

The erase method includes a reading step, a recording step, and anerasing step. In the reading step, a drive reads control data stored inthe filing information area. In the recording step, another driverecords the control data in another medium. Alternatively, a driveequipped with a memory, for example a DRAM, may record the control datain another medium after reading the control data of the opticalrecording medium 30. In the erasing step, the drive erases the filinginformation area that stores the control data. Even if the control dataof the CD-RW medium 30 is accidentally erased by this erase method, theinformation stored in the program area 43 can be read by re-recordingthe control data which is recorded in another medium in the filinginformation area of the CD-RW medium.

In another embodiment of the present invention, a higher level ofsecrecy is possible if the control data of a CD-RW medium in which thecontrol data has been erased by the above-described method is stored inanother medium which is kept physically separate from the CD-RW medium.

FIG. 6 is a block diagram showing one embodiment of the informationrecording/reading system constructed according to the present invention.An input device 65 such as a keyboard or a mouse is disposed so that anoperator can control read, record, and initialization functions to aCD-RW medium. In addition, information needed for the controlling systemis transferred to the system by the input device 65. A CD-R/RW unit 62includes a CD-R/RW drive and an optical recording medium selected fromthe group consisting of CD-R medium and CD-RW medium. An external datastorage unit 67 includes another drive capable of read and writeoperations and another medium that stores control data for access to theuser information stored in a program area of the optical recordingmedium.

A system comprising a CPU (Central Processing Unit) 60 controls theinput device 65 through a bus 66, a display control device 64, a RAM(random access memory) device 61, and the CD-R/RW unit 62. A command tobegin a prescribed operation is inputted by the input device 65 to thesystem. The system then transfers a program to the RAM 61 from theexternal data storage unit 67. Programs for operating the erase methodof the present invention, or other programs for recording and readinginformation are housed in the external data storage unit 67. The RAM 61temporarily stores such programs or various kinds of information, whichare required for recording and reading information of the CD-RW medium,when the system operates.

The display control device 64 controls a display 63 such as a CRT(cathode-ray tube) display or LCD (liquid crystal display) such that theprogram stored in the RAM 61 and window images and icons related tovarious functions of the program are displayed on the display 63. Theexternal data storage unit 67 also stores data for recording or datarequired for operations of the system, in addition to the program foroperating the erase method of the present invention and the program forrecording and reading information to and from the optical recordingmedium.

The CD-R/RW unit 62 includes another CPU and another RAM to record, readand erase information in the CD-RW medium in accordance with a commandfrom the CPU 60.

FIG. 7 is a flow chart illustrating one embodiment of the erase methodaccording to the present invention. The erase method is furtherexplained hereafter with reference to FIG. 7.

When a CD-RW medium is set on the CD-R/RW drive in the CD-R/RW unit 62,as shown in FIG. 6, the CD-R/RW drive reads control data stored in afiling information area (a PMA and a TOC area) of the medium, andrecords the control data in another medium in the external data storageunit 67. Subsequently, the control data stored in the PMA and the TOCarea of the CD-RW medium is erased and the lead-out area of the CD-RWmedium is erased. Using this procedure, the control data in the filinginformation area of the CD-RW medium is erased, resulting in completionof the erasure.

The CD-RW medium, which has been erased, is identified as an unrecordedmedium by an information recording/reading system. Therefore, new datacan be recorded on the medium.

Alternatively, the information stored in the data area can be read byre-recording the control data stored in the external data storage unit67 to the filing information area of the CD-RW medium. This operationcan be performed only by a person who can access the control data.

The program area may be recorded using a writing drive that is capableof recording on an optical recording medium. Alternatively, the mediummay be a hybrid-type medium that includes a recordable area and a ROM(read only memory) area in which pits are previously formed using astamper.

In addition, when the control data is required to be re-recorded to thePMA area of the erased CD-RW medium the following method can also beused. As shown in FIG. 5, system information that is peculiar to thesystem is recorded in the data area (program area). Then the controldata need to access the system information and the user informationstored in the program area is recorded to the PMA 41. Control data isthen recorded in the TOC area and the lead-out area of the CD-RW mediumso that CD drives can read the information stored in the CD-RW medium.If access is allowed only when the additionally recorded systeminformation is verified of the current system information of the systembeing used, the secrecy of the information stored in the CD-RW isimproved.

Further, when an application program and an installation program arerecorded in the program area 43, the secrecy can be improved using amethod in which the application program can be installed only whenadditionally recorded system information is verified to be the same asthe system information of the system being currently used.

As described above in detail, the present invention provides a noveloptical recording medium, erase method, and informationrecording/reading system.

The optical recording medium of the present invention has a high levelof secrecy for user information stored therein.

What is claimed is:
 1. An optical recording medium, said opticalrecording medium comprising:an information area, said information areacomprising: a data area, said data area including a program area in arecorded state containing user information and a user area in anunrecorded state in which user information is stored; and a filinginformation area in which control data for access to the userinformation is to be stored, said filing information area comprising aPMA area in a recorded state, a TOC area in an unrecorded state, and alead-out area in an unrecorded state.
 2. An optical recording medium,said optical recording medium comprising:an information area, saidinformation area comprising: a data area, said data area including aprogram area in a recorded state containing user information and a userarea in an unrecorded state in which user information is stored; and afiling information area in which control data for access to the userinformation is to be stored, said filing information area comprising aPMA area in an unrecorded state, a TOC area, and a lead-out area.
 3. Anoptical recording medium according to claim 2, wherein said informationarea further comprises a recorded portion containing a password.